Abstract
Polycomb group (PcG) proteins have been shown to affect growth and development in plants. To further elucidate their role in these processes in rice, we isolated and characterized a rice mutant which exhibits dwarfism, reduced seed setting rate, defective floral organ, and small grains. Map-based cloning revealed that abnormal phenotypes were attributed to a mutation of the Fertilization Independent Endosperm 2 (OsFIE2) protein, which belongs to the PcG protein family. So we named the mutant as osfie2-1. Histological analysis revealed that the number of longitudinal cells in the internodes decreased in osfie2-1, and that lateral cell layer of the internodes was markedly thinner than wild-type. In addition, compared to wild-type, the number of large and small vascular bundles decreased in osfie2-1, as well as cell number and cell size in spikelet hulls. OsFIE2 is expressed in most tissues and the coded protein localizes in both nucleus and cytoplasm. Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that OsFIE2 interacts with OsiEZ1 which encodes an enhancer of zeste protein previously identified as a histone methylation enzyme. RNA sequencing-based transcriptome profiling and qRT-PCR analysis revealed that some homeotic genes and genes involved in endosperm starch synthesis, cell division/expansion and hormone synthesis and signaling are differentially expressed between osfie2-1 and wild-type. In addition, the contents of IAA, GA3, ABA, JA and SA in osfie2-1 are significantly different from those in wild-type. Taken together, these results indicate that OsFIE2 plays an important role in the regulation of plant height and grain yield in rice.
Highlights
Rice (Oryza sativa) has been a hot spot in plant science research because it is considered a main staple food for more than half of the world’s population
The decreased grain size of osfie2-1 was due to the reduction in grain length and grain width, which resulted in significantly lower 1000-grain weight than wild-type (Fig 1R–1T)
We identify a dwarf and small grain mutant osfie2-1, and found that a fertilization independent endosperm protein OsFIE2 was responsible for the abnormal phenotype of osfie2-1 (Fig 3)
Summary
Rice (Oryza sativa) has been a hot spot in plant science research because it is considered a main staple food for more than half of the world’s population. Its yield is mainly determined by grain weight, spike number and number of grains per panicle, and can be affected by plant height and flowering time [1]. Numerous genes associated with spike number and number of grains per panicle, such as GN1A, TAW1, DEP1, OsSPL14, Ghd, DTH8/. OsFIE2 Affects Plant Height and Grain Yield in Rice
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